I don't like the 'fatal' in that last line. The only thing on Google I can find is [SOLVED] newaliases - unsupported map type: hash which hints at wrong flags during compile-time.The aliases are working, I created a new test alias in postfix-admin that works. So maybe there's nothing really 'fatal' wrong.

Setup; my aliases are virtual and stored in a mysql database. A typical line in `/etc/postfix/main.cf` would look like: